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Modeling of Detonation and Improvment of Engine Performance/Thermodynamic model


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Currently, most aircraft follow manual limits exactly as written. One has exactly as much time as listed in the manual to run at a given setting, and higher settings eat into the time alloted at higher settings. After the timer is spent, the engine can fail at pretty much any time. Most aircraft must drop to the next-lowest engine setting for varying amounts of timeper minute of use to "recharge" this timer. Some planes recharge at a 3:1 ratio, some at 2:1, some are 4:1, and then there's planes that recharge at 1:1 and don't have emergency eat out of combat time. Overall, this results in some engines having drastically higher time limits than others, even on the same settings and/or engines, depending on timeframe, manual limits listed for different aircraft, or other weird inconsistencies. 

 

Not only that, but the timers are linked to instrument panel, which means they won't appear with the technochats most MP servers use (e.g., overheat and damage warnings), and the recharge ratios aren't listed anywhere that I can see. If I take off in my P-38, and combat climb for 5 minutes, do I need to wait 10 or 15 minutes for it to recharge? After entering combat and using emergency for ~4 minutes, is it 8 or 12 minutes to be recharged? There's no way to know besides testing with extensive technochat, as you won't get warnings in most MP servers, and thus can't even figure it out over time in normal missions. It's arbitrary, undocumented, and incredibly frustrating. (This doesn't even get into the more severe issues caused by planes being hampered by 1-minute, low-boost emergency settings that simply don't reflect the reality of what the engines could handle and were overly conservative peacetime limits.)

 

From what I can see, the real killer in most cases was detonation. In detonation (sometimes called engine knock), pockets of fuel-air mixture reach a temperature and pressure that causes them to ignite instantaneously (instead of in the controlled manner caused by the expanding flame front), causing a shockwave and spike in pressure, which can exceed the design limits and do damage.

 What follows below is an excerpt from a P-47D manual.

Spoiler

detonation.png.719c8f8186eeeb93b3559b3eba0c581c.png

As noted above, detonation was contributed to by several factors:

  • excessive MAP
    • higher pressure means the charge is closer to the instantaneous ignition point
  • excessive engine/water/oil temperature
  • excessive CAT (carburetor air temp) 
  • too lean a mixture (This effect is twofold)
    • A richer mixture is more resistant to detonation at a given set of conditions
    • A rich mixture also reduces temperature in multiple ways
      •  introduces more evaporative cooling in the venturi of the carburetor, reducing temperature of the intake charge
      • if combustion is incomplete, unburnt fuel acts as a heatsink when it leaves the engine (This is why many aircraft will actually trail varying levels of black smoke at high power levels. The mixture is purposely over-rich to resist detonation and aid in cooling)
  • insufficient fuel octane
  • Other ignition system malfunctions

It is noted that if inside specified limits (MAP, temperatures, etc), detonation will not occur. Additionally, none of those limits are "time". Once one exits the limits, detonation may occur. Now, exact limits can vary from engine to engine, and changing any one of these factors can cause detonation of varying severities. Running an engine at a slightly too high a MAP may result in only minor detonation. Running an engine at too low a mixture and excessive temperatures may result in rapid, severe detonation that leads to engine failure in fairly short order. However, running an engine within all the limits, detonation will not occur.

 

Spoiler

failureMAPnotime.png.413a0f7ef5466264383a30e433fbbd94.png

This is from a P-47N manual, but further backs up that the limits for detonation are not time-restricted. The limits to not exceed in order to avoid detonation are in MAP, not MAP and time.

 

http://www.wwiiaircraftperformance.org/p-47/p47-26167.html

"Detonation equipment was installed to determine if any flight condition became marginal as to detonation, cooling or improper operation of auxiliary parts. No detonation was observed in level flight up to 65.0" Hg. without water and 70.0" with water. No detonation was observed in climb up to 65" Hg. without water. Detonation occurred at 65.0" with water in climb but was remedied by using a No. 18 water jet. Cylinder head and carburetor air temperatures remained below the limits in level flight. Excessive cylinder head and carburetor air temperatures were encountered in climbs, limiting the duration of any climb to a point where limits are reached... It is recommended that pilots using these higher powers be cautioned concerning the high cylinder head temperatures and carburetor air temperatures which may be encountered in extended climbs or level flight."

 

Again, detonation is not an issue so long as one stays inside CAT and Cylinder head temperature limits, but does occur if the engine is pushed beyond the allowed thermal limits. Pilots need to carefully monitor their engine temperatures when running these high settings (especially in climbs and/or without the use of water) to avoid regions that induce detonation.

 Most engine limits that are time-based do not seem to be based upon a risk of detonation or mechanical failure, but rather a desire to increase engine life. Indeed, many flight manuals (American ones in particular from what I've seen, though I've mostly just read American manuals) generally note that engines can be relied upon to go well beyond their posted limits when necessary:

Spoiler

durability.png.0cbdc474bd17c4861e3dddccadadd103.png

"You'll read G-2 reports of pilots drawing excessive power for long periods. These reports are true."

806208584_Screenshot2021-01-15014258.thumb.png.7a75b437daae21f9e92d77358097b2ab.png

"Inasmuch as it represents a strain on the engine, the pilot must use it with discretion: he must treat it as ammunition which he expends unhesitatingly, but only when the occasion demands." (Italics not mine, but the manual's) Again, pilots are told to use WER unhesitatingly when necessary, but to avoid it outside of necessity. This section also describes the benefits of ADI in preventing detonation. Speaking of which:

One factor that should be noted as being particularly important in reducing and/or preventing detonation is the use of MW-50 or ADI (anti-detonant injection) fluid. P-47s, for example, carried a tank capable of feeding the aircraft for ~15 minutes. This fluid increased combustion efficiency and helped cool the temperature of both the engine and the intake charge (the fuel-air-ADI mix from the carburetor), greatly reducing the chance of detonation.

Spoiler

watershouldbeusedunhesitatingly.thumb.png.6c8c20afabe523e0565879c06cc30e49.png

"water should be hoarded until needed, and then used unhesitatingly" Also note that the D-22 and earlier will only have ~7.5 minutes' worth of ADI injection, whereas the D-25 and later will have 15. This also makes the earlier models' 5 minute injection limit found in manuals make sense, where the limit had a ~50% safe buffer for the pilot to go over by. At no point in the manual is it mentioned that pilots must let the engine rest between uses of ADI, or that they can only use a certain amount at a time. All it says is to save it for when it is needed, then to use it unhesitatingly.

Here's a great chart from a P-38 pilot's manual that shows the detonation regions for P-38J and Ls on "grade 100" (100/130) fuel. (Confirmed by the fact that ANF 28 is listed as 100/130 elsewhere in USAAF flight manuals.) 

Spoiler

P-38detonationchart.thumb.png.0f579d0d51a2bf6aa04f48fd46a62846.png

The actual detonation range is ~2" below the current cleared maximum WER. (Even this chart may also have some wiggle room in it, given that the recommended 44"-2600RPM is technically in the detonation area?) Additionally, while currently in-game, one can extend the time available at a given MAP by reducing RPM, according to the graph, this should actually increase the risk of detonation and reduce the time that could be spent at such a setting, rather than increase it.

 

Again, note how these limits show a maximum CAT, MAP, RPM, and octane/mixture setting, but do not specify a time limit.

 

"Timers" ought not to be hard-coded, but more like a likely time one can safely run a given setting while remaining inside other limits. 

 

I suggest that in aircraft with posted limits, staying within those engine limits ought to result in (theoretically) no limitation to time at a given setting. However, this will have a serious offset, in that pilots will need to carefully monitor the status and temperatures of their carb air, oil, and water/cylinder heads in order to avoid exceeding limits and straying into detonation. This would be far more realistic in terms of how real pilots flew, being able to push aircraft as hard as they wanted, but needing to carefully regulate various systems to avoid pushing the aircraft too hard and damaging it.

 

At continuous engine settings, it should be easy to maintain the optimal temperatures even with fairly low rad, or even closed rad settings. On combat engine settings, temperature should slowly creep up towards maximums and require more aggressive use of cooling (either manually or by the automated systems). Finally, emergency settings should be liable to increase temps rather heavily, especially in low-speed fights where the rads aren't getting sufficient airflow. Approximately at the listed time to 1.5x the listed time, temperatures should begin to push past the maximum, and require backing off to avoid detonation.

 

The further a given aircraft is pushed past any given limit, and the more by which that limit is exceeded, the more severe detonation becomes. When reaching mild detonation, cylinder temps should rise, followed by a slightly self-damaging engine for moderate detonation (which will cause slight power loss and eventual rough running), with severe detonation being quite capable of killing your engine in short order (caused by severe overruns of temperature limits). Most of all, if you don't actually regulate your RPM and MAP well, you can cause detonation by lugging the engine (running too low a RPM for a given MAP).

 

P-47:

  • The P-47s ought to be able to run their WER settings as long as their water supplies last
    • After water supply is exhausted, pilots may need to throttle down and/or open up the intercooler in order to get CAT or Cyl Temps down, as they may be left in a region that could induce detonation without the cooling and anti-detonation effects of the water injection.
      • Max Cyl: 260 (Optimal 230)
      • Max CAT: 55 with water, 35 without
      • Oil: Max 100, Optimal 60
  • A 150-octane P-47 ought to be able to maintain 65" in level flight, but run into thermal issues trying to climb at such a setting
    • When on water, level flight at 70" should be fine, but should lead to thermal issues when climbing.

 

P-38:

  • The P-38's primary limiting factor ought to be CAT. (i.e., the detonation model should primarily be built around CAT, RPM, and MAP)
    • Accounts vary significantly on what the true limiting number was.
      • The manual spec limit is 45°C, but even the chart above shows a max CAT of 60°C
      • http://www.wwiiaircraftperformance.org/p-38/p-38-wayne.html
        • On the extreme end, 70°C was found to be perfectly satisfactory, and outright failure was not encountered until ~90°C
        • This was suggested to be made into a recommendation for 5 minutes at 50° CAT (keep in mind this was for early P-38s without the larger intercoolers and stronger engines, and only 100(130) octane fuel.)
  • I suggest 60°C limit for 3000RPM, and 45°C limit for 2600RPM (the chart above shows detonation at continuous. This could be that even the chart is conservative, or that the higher CAT may lower the detonation limit at 2600RPM)
    • 150 octane P-38s do not currently exist, but absolutely should as I explained in this post. If they are added, allowable CAT at a given MAP should increase, though at 70" WER, it should probably remain at 60°C

 

FW-190A:

  • FW 190 has 10 minutes of boost supply, with no limit or recharge time specified
  • There's no CAT reading for 190s (since they had no carburetor), so the primary limit should probably be cylinder head and/or oil temperature.
    • Note that the max Cyl Temp is 180, a far cry from the P-47's 230-250. This may (If I understand correctly) partially represent the restriction that a lower octane fuel causes in its propensity to detonate. (IIRC the 190A used B-4 fuel, which had a much lower octane than the P-47s 100/130)
  • Cylinder heads temps are fairly easy to control with the gills, but the oil cooler has no real control besides heavily reducing all the other temperature
  • Given that the main way pistons are cooled is with oil, exceeding oil max may be a good metric here? 
    • Long periods of time at high power may cause oil cooling capacity to become overwhelmed. 
    • Alternatively, particularly high exit temperatures may result from prolonged usage of high power settings (while this will eventually lead to an increase in general oil temperature as well, exceeding max allowable oil exit temperatures may represent excessive piston temperatures and a high likelihood of oil detonation)

 

FW-190D:

  • 30 minutes of boost supply, but is specifically noted in the manual that it can only be used 10 minutes at a time, then must be pulled back to combat for 10 minutes in order to use it again.
    • Since it is specifically noted that there must be a cool-down period between uses, it seems like it would make sense that such high boosts push oil and/or water temps towards the limit, but cool them back down after 10 minutes on combat.
      • It also makes sense that the water injection allows the engine to run a setting that would overheat and cause detonation in a much shorter timeframe (3 mins) normally.
  • It seems the systems could keep up with combat quite easily

 

The main issue I see with a more thermodynamic system is that if the thermodynamics are currently too simple, it may be too easy to abuse the system by throttling back to 0 for a moment to drop temps a few degrees, then simply go back to maximum. By simulating overall block temperature and thermal mass (simply how much mass there is of coolant, engine block, etc.), it should be easy to create a system which has thermal inertia, and won't be able to be instantaneously plunged from 10 degrees over a limit to 10 under. Additionally, heavy thermal cycles are damaging to the engine in their own way, if this still turns out to be abusable and needs to be discouraged.

 

I'll freely admit I'm no expert, and mainly have a detailed knowledge of American aircraft. If anyone has any input, suggestions, or sources at all, I'd be glad to see them!

 

All this being said, I think modeling such a system would be a quantum leap forward in comparison to the current engine timers with arbitrary lengths, recharge ratios, and behavior patterns.

Edited by DJBscout
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  • 2 weeks later...

I don't think it's necessarily the Engine Timers that annoy me the most, but the Damage that running out of Time does without Warning, meaning the instant, immediate Catastrophic Damage and the extremely long Cooldown Time.

 

Engine Timers should only be for the Emergency Settings, any lower Settings should be considered Continuous. Also any mode that can be run for 15 and more Minutes should be counted as Continuous and exceeding shouldn't result in any Damage.

 

Rechare Time has to be shorter. 1 Minute of "Continuous Power" should recharge 1 Minute of Emergency Power, 2 Minutes at "Combat Power" should recharge 1 Minute of Emergency Power for Non-Water-Injected Planes.

 

Creeping Damage should be modelled in a CLEARLY AUDIBLE SEQUENCE, no Surprise Engine Insta-Death with no Warning if there is no Technochat.

  1. after exceeding the Limit tp 150% (1:30 for a 1:00 Timer, 7:30 for a 5:00) of your Timer there should be a "Rough Running" Sound as a Warning and some Power Loss, but not yet lasting Damage
  2. Limiter Time 200% (2 Minutes of a 1 Minute Timer, 10 Minutes of a 5 Minute Timer) permanent Damage should start to accumulate slowly, down to about 80% max available when reaching 400% Engine Timer (4:00 of a 1:00 Timer, 20 Minutes of a 5 Minute Timer, a 1000hp Engine is now down to 800hp, enough to get home, but not enough to have a competitive Edge anymore)
  3. Limit Time 400% to 800%  (4 Minutes to 8 Minutes of a 1 Minute Timer, 20 to 40  Minutes of a 5 Minute Timer) Damage should accumulate to 0% Power by the End.

I think this is a good compromise to effectively Limit Power Spam but also free up Pilots to use Power even past Limits in Emergencies without instant Engine Death and rewards flying lower settings for shorter Cooldowns.

Edited by 6./ZG26_Klaus_Mann
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On 29/1/2021 at 11:25 AM, 6./ZG26_Klaus_Mann said:

I don't think it's necessarily the Engine Timers that annoy me the most, but the Damage that running out of Time does without Warning, meaning the instant, immediate Catastrophic Damage and the extremely long Cooldown Time.

 

Engine Timers should only be for the Emergency Settings, any lower Settings should be considered Continuous. Also any mode that can be run for 15 and more Minutes should be counted as Continuous and exceeding shouldn't result in any Damage.

 

Rechare Time has to be shorter. 1 Minute of "Continuous Power" should recharge 1 Minute of Emergency Power, 2 Minutes at "Combat Power" should recharge 1 Minute of Emergency Power for Non-Water-Injected Planes.

 

Creeping Damage should be modelled in a CLEARLY AUDIBLE SEQUENCE, no Surprise Engine Insta-Death with no Warning if there is no Technochat.

  1. after exceeding the Limit tp 150% (1:30 for a 1:00 Timer, 7:30 for a 5:00) of your Timer there should be a "Rough Running" Sound as a Warning and some Power Loss, but not yet lasting Damage
  2. Limiter Time 200% (2 Minutes of a 1 Minute Timer, 10 Minutes of a 5 Minute Timer) permanent Damage should start to accumulate slowly, down to about 80% max available when reaching 400% Engine Timer (4:00 of a 1:00 Timer, 20 Minutes of a 5 Minute Timer, a 1000hp Engine is now down to 800hp, enough to get home, but not enough to have a competitive Edge anymore)
  3. Limit Time 400% to 800%  (4 Minutes to 8 Minutes of a 1 Minute Timer, 20 to 40  Minutes of a 5 Minute Timer) Damage should accumulate to 0% Power by the End.

I think this is a good compromise to effectively Limit Power Spam but also free up Pilots to use Power even past Limits in Emergencies without instant Engine Death and rewards flying lower settings for shorter Cooldowns.

I don't understand your problem.  I'm talking about the bf109 on which I carry out my missions.  I know that Ata 1.2 and I go quiet.  Ata 1.3 attention, only 30 minutes, then reduce pressure and let the engine rest.  Ata 1.4 only 1 minute use only at take off.  With these simple rules I don't risk damaging the engine.  No real driver in IIWW would have risked the engine, would have disengaged or would not have accepted a tactic that is not convenient for him but for his opponent.

Edited by Startrek66
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3 hours ago, Startrek66 said:

I don't understand your problem.  I'm talking about the bf109 on which I carry out my missions.  I know that Ata 1.2 and I go quiet.  Ata 1.3 attention, only 30 minutes, then reduce pressure and let the engine rest.  Ata 1.4 only 1 minute use only at take off.  With these simple rules I don't risk damaging the engine.  No real driver in IIWW would have risked the engine, would have disengaged or would not have accepted a tactic that is not convenient for him but for his opponent.

First of all it's 1.15ata/2300 for cruise.

 

The Issue is more with American Planes, for which the Handbook Values didn't reflect the reality of War and what the Engine could take. The WWII Pilot we have talked to told us that in Combat the Pilots used as much Power as they needed to win without regard for time.

 

Once you have tried P-40 or P-47 on TAW, you will know why the current System is very frustrating.

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If a powerful plane engine isn't capable of breaking its self rapidly due to incorrect input by the pilot, it's because its design included features that limit the power or speed the engine can operate at. Before engine computors, most designers would prefer to have the pilot have access to as much power as possible, even if it means the pilot is capable of inputting settings that could cause the engine to rapidly break. Although, other designers only allowed pilots the freedom to slowly break their engines through settings that caused excess wear and tear at the price of not giving the pilots access to settings that might give them more power when needed.

 

 Some engines should absolutely fail quickly and without any warning under certain conditions cause by incorrect management.

 

Timers aren't a bad approximation, but it would certainly be better if the actual cause of failure was modelled instead.

Some that come to mind and can end an engine in short order are:

  • Pre-spark detonation/knock from over pressured or overheated cylinders.
  • Backfire in the supercharger from high RPM, pressure or temperature.
  • Any number of problems from more RPM than their engines could mechanically handle such as bent conrods or bearing failure leading to crank shearing.
  • Radiators perforated due to localised boiling.
  • Hydraulic lock in downward pointing pistons from unburnt fuel or oil.
  • Oil thinning or localised boiling.
  • Oil starvation due to g-force
  • Cascade issues caused by something else on this list going wrong
  • Turbo/super charger over speed and over pressure problems

We have timers because simulating such complexities are hard, but of course it would be great to see it done.

 

 

Edited by [DBS]Browning
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I’d like to see more detailed damage due to over heating your radiator/cylinders/oil as well. I feel the heat buildup is not really an issue in IL2. I wish there was more to managing heat buildup in this game. Run your engine as hard as you want as long as you manage your heat.  I think the heat build up is not quick enough in this game. You literally leave the radiator % on a specific number and never touch it again.
 

Also, coolant leaks due to damage is of no concern to anyone in this game. I’ve had hundreds of leaks with no issues getting home. Seems like planes have an infinite  amount of coolant.

Edited by VBF-12_Esco
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4 hours ago, VBF-12_Esco said:

Run your engine as hard as you want as long as you manage your heat.

 

I think this seems a straightforward and practical solution. While an engine run over its rated continuous parameters will experience greater wear-and-tear even if it's kept cool, and may- eventually- fail, it's not at the kind of timeframe represented in the game. I'd be happy to take a score penalty for engine overuse to represent the increased maintenance, or something like that. As far as in-game, in-combat effects, it should be heat that is the limiting factor on engine performance.

 

On 1/31/2021 at 1:16 PM, Startrek66 said:

No real driver in IIWW would have risked the engine, would have disengaged or would not have accepted a tactic that is not convenient for him but for his opponent.

 

Late to this comment but basically every wartime account I've read has said the opposite of this. Americans and Soviets regularly redlined their engines in combat, because no pilot valued the workload of the maintenance crew over winning the fight. And they certainly wouldn't disengage and go home while a buddy is in combat just because they've been running at full power for a few minutes.

 

Either way, the timers given in-game seem overly conservative. Here's a memorandum from the Allison company describing the emergency test for the V-1710-91 engine. They ran the engine for seven and a half hours at 3000RPM and 75". It didn't kill the engine, let alone within five minutes. Granted that's a late iteration of the Allison, but it's not like it was noted as exceptionally more robust than earlier iterations.

 

Even OP's suggestions are far more conservative than what historical data and pilot anecdotes suggest- which is that in-flight, the main limiting factor on engine power was coolant, rather than severe degradation after just a few minutes of full power.

Edited by Catgut
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3 hours ago, Catgut said:

While an engine run over its rated continuous parameters will experience greater wear-and-tear even if it's kept cool, and may- eventually- fail, it's not at the kind of timeframe represented in the gam

 

That's not true.

Even car engines that don't have an engine control system can be destroyed in a short time frame if you rev them well over their red-line, even if the temps are still normal.

Unlike car engines, most wartime plane engines can be destroyed by over pressure, supercharger issues and various other methods.

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1 hour ago, [DBS]Browning said:

 

That's not true.

Even car engines that don't have an engine control system can be destroyed in a short time frame if you rev them well over their red-line, even if the temps are still normal.

Unlike car engines, most wartime plane engines can be destroyed by over pressure, supercharger issues and various other methods.

*Can Be*? Yes. Are every time without fail after x amount of time? Hardly.

 

Some engines can fail regardless of whether it is abused or not. Some engines can withstand unbelievable abuse. The point is to say the system we have is mostly absurd and neuters planes like the p-40, whose allison 1710-39 with 8:8 supercharger was noted for being simple and incredibly robust. Pilots regularly boosted it to over 65" inches in combat and some british squadrons even boosted it to over 70" in the desert for up to 20 minutes at a time without a reported failure.

 

It's all here: https://ww2aircraft.net/forum/threads/allison-v-1710-39-power-output-at-sea-level-as-installed-in-p40e.44909/

 

 

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2 hours ago, [DBS]Browning said:

 

That's not true.

Even car engines that don't have an engine control system can be destroyed in a short time frame if you rev them well over their red-line, even if the temps are still normal.

Unlike car engines, most wartime plane engines can be destroyed by over pressure, supercharger issues and various other methods.

 

Going back to your previous post:

 

On 1/31/2021 at 6:07 PM, [DBS]Browning said:

it's because its design included features that limit the power or speed the engine can operate at.

 

The question is whether, as a general rule, WEP represents riding the edge of the engine's breaking point, or a design-limited level that can be sustained but for maintenance/heat reasons should not be. To take the Allison as an example, it was limited to the maximum pressure that it was considered to run safely at, which changed throughout the war- there's a document I've seen in which an officer complains that the Brits were removing their limiters and running their engines at 70" (!) for extended lengths of time without issue.

 

In the memo I linked, the Allison ran seven and a half hours in bench testing at a setting that you get only a few minutes from in-game. DB605 engines had a run-in procedure involving 5 minutes at the setting that breaks your engine after just one minute in-game. Soviets abused the hell out of their lend-lease P-39s. Everyone abused the poor P-40. You'd think that if all you had to do to kill your plane was run it at max throttle for sixty-one seconds, it'd be a reasonably common occurrence.

 

So, if we have to choose a single baseline model for how engine limits should be handled, and our options are:

1. WEP power generally represents riding the bleeding edge of imminent engine destruction, or

2. WEP power generally can be sustained, but is prohibited for maintenance reasons and/or will quickly overheat your engine if you're not careful

 

It seems to me like the latter is closer to reality, and still permits break-the-engine-in-two-minutes behavior to be implemented for relevant aircraft- where the historical data supports it- through heat generation.

 

I don't think it's valid to simply assert that most designers would let the pilot kill the engine in seconds, and set engine timers for WEP on that basis.

Edited by Catgut
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8 minutes ago, Catgut said:

 

I don't think it's valid to simply assert that most designers would let the pilot kill the engine in seconds, and set engine timers for WEP on that basis.

 

 

I don't have time for a full reply right now, but consider that my 1.2L car from the 90s is more than capable of destroying its engine if I give it incorrect inputs such as full throttle and full clutch. The designers of my car engine where, in general far more conservative than the designers of high performance aircraft engines and there are far fewer controls and ways to damage my car engine than there are in planes. 

Revving my car significantly above the red line will kill the engine in a somewhat predictable amount of time as well. 

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3 hours ago, [DBS]Browning said:

 

I don't have time for a full reply right now, but consider that my 1.2L car from the 90s is more than capable of destroying its engine if I give it incorrect inputs such as full throttle and full clutch. The designers of my car engine where, in general far more conservative than the designers of high performance aircraft engines and there are far fewer controls and ways to damage my car engine than there are in planes. 

Revving my car significantly above the red line will kill the engine in a somewhat predictable amount of time as well. 

 

That's cool and all, but if we have source documentation saying that an Allison engine can be run for hours at WEP, why does the fact that you could kill your 90s car through, as you say, incorrect inputs, mean a P-39 should break after a couple minutes of full power in-game with otherwise correct inputs?

 

I mean, I never said that things like overrev shouldn't cause damage, just that running engines at maximum power using otherwise correct settings- when there is documentation showing that they could do so, irrespective of the time limits given in the manuals- shouldn't kill them without warning after an arbitrary amount of time. They should run until they overheat, because the evidence suggests that is what they did IRL.

 

If you've got ideas for incorrect control inputs that should cause engine damage but aren't currently modeled, great! I'd absolutely take a system where you can run your engine at high power theoretically indefinitely, but greatly increase the risk of inadvertently damaging it through bad input, over one where you can run your engine at high power perfectly for one minute and then it explodes at random.

Edited by Catgut
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14 hours ago, Catgut said:

Late to this comment but basically every wartime account I've read has said the opposite of this. Americans and Soviets regularly redlined their engines in combat, because no pilot valued the workload of the maintenance crew over winning the fight. And they certainly wouldn't disengage and go home while a buddy is in combat just because they've been running at full power for a few minutes

Mine was a statement based on a duel between opponents without, however, that there was a friend in difficulty. In this case it is obvious that the friend must help himself

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17 hours ago, [DBS]Browning said:

 

I don't have time for a full reply right now, but consider that my 1.2L car from the 90s is more than capable of destroying its engine if I give it incorrect inputs such as full throttle and full clutch. The designers of my car engine where, in general far more conservative than the designers of high performance aircraft engines and there are far fewer controls and ways to damage my car engine than there are in planes. 

Revving my car significantly above the red line will kill the engine in a somewhat predictable amount of time as well. 

 

Overreving destroys engines when the piston starts moving faster than the valves can compensate, and they start colliding (unless you moneyshift quite aggressively, in which case you probably throw a rod or something in addition to the valves and pistons kissing).

 

Almost all of the planes in the sim have RPM governors, which will try to maintain a set RPM regardless of throttle input (you can think of prop pitch as like a continuously variable transmission controlled by the governor). There's no reason to deliberately run an engine at RPMs that will result in piston-valve contact (no emergency procedure ever read "let the pistons kiss the valves a bit, for MAX POWER"). Thus, a properly functioning governor will never drive RPM so high, and no RPM setting available should result in immediate destruction of the engine through the same mechanism as you see in your car.

 

Incidentally, I do know of one account of a 109 forced to fly at maximally fine pitch:

Quote

The propeller governor on Uffz. Georg Genth's aircraft then malfunctioned, and he aborted the mission. He had to evade some P-47s, was then taken under fire by German Flak, and decided to land on Koln-Butzweilerhof for fuel and servicing. The airfield had just been bombed, and a Fw 190 landing ahead of Genth taxied into a crater. Genth landed between the craters and taxied to the refueling point. The groundcrewmen tinkered with his propeller mechanism and announced that it was fixed. Genth was anxious to leave before dark and get back to Plantlunne for the base Christmas party, and took off despite warnings from the technical officer and the weatherman. He took off into a low-lying cloud, and immediately discovered that the propeller pitch governor had been connected backwards, and could not be gotten out of fine pitch. His radiator boiled over, and his engine began overheating. Genth had to drop below the overcast and crash-land his aircraft, which overturned in a farmyard.

From Caldwell, The JG 26 War Diary, vol 2, p393 .

 

So even with the prop effectively stuck in "first gear" and the governor disabled, the problem was heat dissipation, not overrev trashing the valves.

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If they have the time I would like the developers to give the single player options/multiplayer servers the options for the timers as I think that would create more diverse gameplay.

- There could be the standard timers we have in the game as a first option.

- We could then have a mode where there is only a timer for the emergency setting 

- Lastly we could have a no timer option.

Pilots will still have to manage the huge drain in fuel and the temperatures that shoot up while at these settings and in planes with automatic settings keep in mind the radiators will open with extended use. In terms of recharge times/ratios I would also like this to be a server/player choice with maybe a slider.

This should allow more restrictions to get more realistic speeds in cruise or more relaxed gameplay where planes can use their advantages like 109s with 1.4ata duration and the p40/p39 with its unpleasant timers. One more suggestion is for an audible indication of when timers are at the limits, maybe as the timer runs out the rpms get shaky with engine sound changing in tone but this is not sudden but an extended period which can be observed. I am not going to say what is realistic or not but to let the people decide 

Edited by -Astra-TheRedPanda
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I hope they don't splinter the multiplayer environment by allowing per-server timer settings. It would be annoying to join one server and need to manage my engine one way, and then have to relearn the same plane for a different server with different engine settings. Besides that, none of the three options you propose, Astra, actually resolve my issues with engine management in this sim.

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On 3/3/2021 at 10:57 AM, Charon said:

I hope they don't splinter the multiplayer environment by allowing per-server timer settings. It would be annoying to join one server and need to manage my engine one way, and then have to relearn the same plane for a different server with different engine settings. Besides that, none of the three options you propose, Astra, actually resolve my issues with engine management in this sim.

It would be an easy solution because people would only fly the servers without timers because they are stupid and historically inaccurate. 

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5 hours ago, =AW=drewm3i-VR said:

... stupid and historically inaccurate. 

 

Ironically this is a fair description of multiplayer much of the time.

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So basically extend the timers so that American planes can run up to 15mins of Emergency Power. Makes LW planes use Emergency indefinitely, RAF planes use it for very long and VVS planes not having it at all. On top of that make Emergency rechargable so that we all use Emergency only. Not good.

 

Sadly going the way Browning described it is not possible at the moment. So maybe give sturdy engines sturdier timers and lesser penalties. I can`t see why not since obviously some engines could take a lot more beating over the red line than others. That said, activating a penalty clock with Emergency and stopping it should place the clock exactly at the spot for the rest of the flight until we get a new plane. Also, enabling the audible rough running engine sound effect should enable probability of random effects to keep people from gaming the clock.

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On 3/5/2021 at 10:37 AM, Mac_Messer said:

So basically extend the timers so that American planes can run up to 15mins of Emergency Power. Makes LW planes use Emergency indefinitely, RAF planes use it for very long and VVS planes not having it at all. On top of that make Emergency rechargable so that we all use Emergency only. Not good.

 

Sadly going the way Browning described it is not possible at the moment. So maybe give sturdy engines sturdier timers and lesser penalties. I can`t see why not since obviously some engines could take a lot more beating over the red line than others. That said, activating a penalty clock with Emergency and stopping it should place the clock exactly at the spot for the rest of the flight until we get a new plane. Also, enabling the audible rough running engine sound effect should enable probability of random effects to keep people from gaming the clock.

La-5, La-5FN, all of the Il-2s, I-16, MiG-3 are the Soviet Planes that would benefit from more useful power as well.
And indirectly the P-40, Hurricane, P-39, Spit Mk.Vb and A-20 are also Russian and the Allison Powered ones bitterly need every ounce of Power they can get.

 

Unless of course by "Russian" you mean Yak.

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All planes benefit, that`s my point. So all players benefit whereas not all planes are "broken". At least not in the same way. This is the sole reason why the overheat mechanics is such a complicated problem.

 

The Soviet planes have roughly on par performance and are hard to overheat but have no Emergency.

 

The RAF planes have roughly on par performance but overheat quickly outside Continuous.

 

The USAF planes (except the P51 and P38) have poor performance in Combat and overheat quickly.

 

The LW planes don`t overheat easily, have best performance in Combat mode and leave everything else behind in Emergency performance.

 

We need a recipe to level them on gameplay standpoint, while not changing the whole idea from the ground up.

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6 hours ago, Mac_Messer said:

The Soviet planes have roughly on par performance and are hard to overheat but have no Emergency.

All Soviet (including Lend Lease) Planes that aren't a Yak, Pe-2 or LaGG-3 have Emergergeny Power Settings that limit what they can do. A La-5FN chasing an A-5/U-17 for example will run out of breath 5 Minutes before the 190 has to cut it's C-3 Injection. Or an La-5 chasing a 190A-3 will run into similar Issues.

 

7 hours ago, Mac_Messer said:

The USAF planes (except the P51 and P38) have poor performance in Combat and overheat quickly.

Well, as an avid P-40 and P-47 flyer, the 5 Minute Limitation is especially annoying given the extremely long recovery time. It basically loses you battles you could otherwise fight evenly

 

7 hours ago, Mac_Messer said:

The LW planes don`t overheat easily, have best performance in Combat mode and leave everything else behind in Emergency performance.

The 190As overheat very quickly in long Climbs and the 109s overheat their Oil constantly. In the 109s there is also a huge Drag Penalty when the Radiators open, much, much worse than any other Plane ingame.

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Hello.

I simply do not think that any engineer or any military plane tester will have allow to let planes be used in war condition with engine that can be broken so suddenly and without any warning, as in game. That's simply too dangerous for pilots who may fight for their life. They may be not so well trained to keep their self control and think at engine management even if you have someone on your six firing at you.

I do believe that devs have greatly overdone engine limitation, if no temperature issues engines should mostly start to loose power and RPM, have vibration,...long time ago before breaking.

As I know, most of engine can still work without a piston because of bullet impact.

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2 minutes ago, c6_lefuneste said:

Hello.

I simply do not think that any engineer or any military plane tester will have allow to let planes be used in war condition with engine that can be broken so suddenly and without any warning, as in game.


Exactly. When Engines were having very sudden Problems, they were often either pulled from Service or Limited. Especially when important People fall Victim to such Issues.

Best known example was Hans Joachim Marseille, who died following an Engine Fire in a very Early Bf109G.

This was the reason the 1.3ata lock was introduced for all Planes until it's release when changes were made to make the Engine durable enough to take the high Power Setting reliably.

All Engines ingame are running Settings that are safe to run.

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1 hour ago, 6./ZG26_Klaus_Mann said:


Exactly. When Engines were having very sudden Problems, they were often either pulled from Service or Limited. Especially when important People fall Victim to such Issues.

Best known example was Hans Joachim Marseille, who died following an Engine Fire in a very Early Bf109G.

This was the reason the 1.3ata lock was introduced for all Planes until it's release when changes were made to make the Engine durable enough to take the high Power Setting reliably.

All Engines ingame are running Settings that are safe to run.

Engine fire may be the only critical event to keep. I read lot of B29 teams were lost due to engine fire, untill they made B29 engine more reliable.

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If you look at both the civil and combat losses for almost any plane type in the war, engine failure without fire is very, very common.

This list is a good example, but there are many more out there that tell the same storey.

Engines cut in combat, out of combat, in speed tests, on landing; all the time.

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2 hours ago, [DBS]Browning said:

If you look at both the civil and combat losses for almost any plane type in the war, engine failure without fire is very, very common.

This list is a good example, but there are many more out there that tell the same storey.

Engines cut in combat, out of combat, in speed tests, on landing; all the time.

Well, yes, but those are also mostly not structural failures of the Engines, but Maintenance Failures. Faulty Fuel Pumps, cracked Radiator Hoses, bad Radiator Welds and so many Things that are unrelated to Power.

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19 minutes ago, [DBS]Browning said:

You might be right, I don't know, but I'd like to know how you came to that conclusion. 

Civilian Aviation Statistics and Crashes with WWII Birds today. Most of the Time Engines fail due to Human/Pilot Error, Maintenance Mistakes and hastiness.

 

Sometimes there is a Hydraulics Fault, something as simple as a slightly sticky Valve that would unstick or be detected during a proper Run-Up. Fail to do that, open the Throttle and the Engine overrevs, normally on Lift-Off, when you have other things to worry about and "BOOM", split Crank. Yes, the Engine failed spectacularly, but the Cause wasn't a structural Problem with the Engine, but bad Prop Hydraulics.

 

Water in the Fuel. Fail to check it properly before getting in, the Engine may run for just long enough to get you off the Ground, and then lose Power. Results in running out of Runway and putting it in a Hedge.

 

Too little Oil, happens surprisingly often.

 

While doing Maintenance, getting distracted, putting on an Inspection Cover, but not tightening it down, Pilot comes along, gets in, flies off and the Oil just goes to 0 in a Manner of Minutes, Massive Engine Failure.

 

Young Mechanics love to Crossthread Spark Plugs. Watch those fly.

 

A lot of things happen that make otherwise fine Engines fail.

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Been reading thru some combat reports from P-51, P-47, P-38 and Spit pilots. The same story comes up again and again: someone spots bad guys - everyone jettisons their tanks, goes max boost and max rpm. Only after the fight is over in 10, 15, 20 mins or however long it takes do they finally go back to cruise settings.

 

Imagine Bud and Chuck flying together in a dogfight. 109 gets onto Yeager's tail. He screams into the radio telling Bud to clear his 6. Bud responds: "No can do, I ran out of my emergency and combat timers. I'll RTB and recharge my timers. Cya!" Yeager - "WTF, get back here immediately you son of a - BANG BANG BOOM AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAARGH!!!" 20mm shells tear Yeager's plane into pieces - Yeah never read anything like that in a combat report.

 

Pls devs gib a more realistic system.

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An amusing anecdote from Lipfert's book, p85:

Quote

At this time my friend Heino Sachsenberg was again the subject of conversation. He hated and despised dogfighting. He refused to spar with the enemy, instead he made his kills with elegance and superiority. He always maintained "I am the highest of all. Should I fly somewhat too low, inadvertently or from necessity, then I'm faster than any other!"

 

...

 

Once I was allowed to fly Sachsenberg's aircraft. During the flight, I was unable to find a speed at which his "Yellow 8" would run smoothly. But why? Quite simply, Heino knew only one position for the throttle in the air -- wide open!

 

The Crimean weather was also not to Heino's taste. The clouds usually hung quite low, and so he flew close beneath the clouds at full throttle.

 

Dave Hastie also has an interview where he describes his engine failing dramatically shortly after he went to WEP:

 

Quote

Of course, in a dust, then you're using power. I think I had my throttle through the gate, because we had a gate on the throttle. Full throttle was up to the end of the travel, of the quadrant. And there was a little gate, and you could push it through there, for not longer than I think it was supposed to be a minute, and then the engine blew up. I suddenly got a tremendous vibration in the aircraft, and black smoke came pouring out of it, and there were flames in the bottom of the cockpit.

 

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On 1/29/2021 at 2:25 AM, 6./ZG26_Klaus_Mann said:

I don't think it's necessarily the Engine Timers that annoy me the most, but the Damage that running out of Time does without Warning, meaning the instant, immediate Catastrophic Damage and the extremely long Cooldown Time.

 

I think the idea of audible warnings is clearly gamey. I've never heard of anything like that in real life. The temperature gauges should give warning, sure, but at the point where an engine starts making abnormal noise, something is toast. It's not going to fix itself just because the pilot throttles back. Even "knock", despite the name, isn't audible in airplanes, and that can destroy an engine in seconds:

 

Quote

Most of you will have heard this sound, a fairly rapid, high-pitched knocking from an automobile engine. It usually occurs when laboring up a hill, with the manual transmission in too high a gear (low engine RPM), and the gas pedal well down (high manifold pressure). That’s detonation. You won’t hear it in an airplane for a couple of reasons. First, there are no mufflers on airplanes (see below), and the high noise level masks the sound. Second, the audible “pitch” of the sound is directly related to the size of the cylinder bore, with “big-bore” aircraft engines emitting a much lower-pitched sound. That sound is far more likely to be lost in the noise of the engine itself.

 

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1 hour ago, 6./ZG26_Klaus_Mann said:

Civilian Aviation Statistics and Crashes with WWII Birds today.

I'd be very, very surprised if any Civilian Operator exceeds the engine handbook limits, so naturally there will be few, or no, failures from exceeding limits for civil operators.

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14 hours ago, Mac_Messer said:

The Soviet planes have roughly on par performance and are hard to overheat but have no Emergency.

 

I don't find that to be my experience in flying Yaks*. You have to keep the water radiator open to keep the coolant temperature down and full power low-speed climbs will quickly overheat the engine. 

 

*Mainly the Yak-1 and Yak-7B.

Edited by LukeFF
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1 hour ago, dogefighter said:

Been reading thru some combat reports from P-51, P-47, P-38 and Spit pilots. The same story comes up again and again: someone spots bad guys - everyone jettisons their tanks, goes max boost and max rpm. Only after the fight is over in 10, 15, 20 mins or however long it takes do they finally go back to cruise settings.

 

Imagine Bud and Chuck flying together in a dogfight. 109 gets onto Yeager's tail. He screams into the radio telling Bud to clear his 6. Bud responds: "No can do, I ran out of my emergency and combat timers. I'll RTB and recharge my timers. Cya!" Yeager - "WTF, get back here immediately you son of a - BANG BANG BOOM AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAARGH!!!" 20mm shells tear Yeager's plane into pieces - Yeah never read anything like that in a combat report.

 

Pls devs gib a more realistic system.

I don't think most aerial dogfights lasted for even 10 minutes. Not least because at the end of a long flight, most pilots would not have the fuel to fight at full boost for that long. Most combat was much more fuel limited than what we have in the sim. An actual 20 minute dogfight in a spitfire at full boost would consume a huge chunk of your fuel.

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15 minutes ago, Charon said:

I think the idea of audible warnings is clearly gamey. I've never heard of anything like that in real life. The temperature gauges should give warning, sure, but at the point where an engine starts making abnormal noise, something is toast. It's not going to fix itself just because the pilot throttles back. Even "knock", despite the name, isn't audible in airplanes, and that can destroy an engine in seconds:

Well, pretty much all the ingame Engines have restrictions on how much Manifold Pressure could be run at any given RPM, expressly because running high MAP and low RPM causes knock.

In an Aircraft with a Constant Speed Prop the Car Scenario doesn't apply, as you normally never run less than Max RPM at Max MAP.

The Engines ingame, except for the P-40, are limited to Manifold Pressures that don't allow for knock if the Engines are set correctly, meaning Rich Mixture and High RPM.

 

14 minutes ago, RedKestrel said:

I don't think most aerial dogfights lasted for even 10 minutes. Not least because at the end of a long flight, most pilots would not have the fuel to fight at full boost for that long. Most combat was much more fuel limited than what we have in the sim. An actual 20 minute dogfight in a spitfire at full boost would consume a huge chunk of your fuel.

Well, I've had plenty of Fights and Tailchases that exceeded 10 and even 20 Minutes. Too often unfortunately cut short by the Engine Failing due to unrealistic Failure. Especially when trying a getaway in a P-47 I would find myself at Max Speed and with Water to spare and the engine failed exactly 5:30.

This is of course on more realistic Servers, flying Coordinated.

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Engine timers are obviously unrealistic, but what do you replace them with that both:

 

- Encourages realistic flying

- Is based on objective, recorded data about the engine, not done by "feel"

 

Would it be based on the expected service lifetime of the engine, maybe? I don't know. I imagine the reason manual advice is used is because it's a concrete number that can be lifted without accusation of bias

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